Flexible device for deflecting charged particles



v NOV. 3, 1970 HYQTA FUJITA- ETAL 3,538,468

FLEXIBLE DEVICE FOR DEFECTING CHARGED PARTICLES Filed April 14, 1969 FIG. F/G.2

PRIOR ART United States Patent Office 3,538,468 Patented Nov. 3, 1970 3,538,468 FLEXIBLE DEVICE FOR DEFLECTING CHARGED PARTICLES Hyota Fujita and Kazuhiro Ueda, Amagasaki, Japan, as-

signors to Mitsubishi Denki Kabushiki Kaisha, Tokyo, Ja an F Filed Apr. 14, 1969, Ser. No. 815,617 Claims priority, application Japan, Apr. 16, 1968, 43/25,401 Int. Cl. H01f 7/00 US. Cl. 335-212 5 Claims ABSTRACT OF THE DISCLOSURE A flexible beam conduit extends centrally through several juxtaposed ring-shaped magnets having opposed main faces tilted toward each other with ball bearing type supports interposed between the magnets. One pair of opposed non-magnetic retainers are fixed respectively to pole pieces of each magnet to sandwich the conduit between them to maintain its predetermined position relative to the pole pieces. Selected ones of the magnets are suitably rotated with respect to the adjacent magnets to curve the conduit into any desired curvature while establishing a field for moving a beam of charged particles along the curved axis of the conduit.

BACKGROUND OF THE INVENTION This invention relates to a device for deflecting a beam of charged particles.

Conventional types of such deflection devices comprise a section of beam conduit curved into a predetermined curvature to guide a beam of charged particles within the same, and an electromagnet having a geometry conformed to the predetermined curvature and encircling one portion of the curved section to deflect the beam of charged particles only along the longitudinal axis of the curved section of conduit. Those devices are satisfactory for applications where the beam of charged particles are to be deflected along a predetermined fixed curvature. However, it is high- 1y desirable to variably deflect the beam of charged particles and particularly to provide a flexible conduit for industrial and medical purposes.

SUMMARY OF THE INVENTION Accordingly it is an object of the invention to provide a new and improved device capable of varying the direction of a beam of charged particles, at will, and in a simple manner. 7 1

The invention accomplishes this and other objects by the provision of a flexible device for deflecting a beam of charged particles comprising a section of beam guide conduit and annular magnet means encircling at least one portion of the section of beam conduit. The device is characterized in that the section of beam conduit is flexible, that the magnet means includes a plurality of annular magnets disposed in juxtaposed relationship, each of the magnets having a pair of opposite main faces tilted toward each other, and imparting a deflection of one unit to the beam of charged particles, and that one supporting member is interposed between each pair of adjacent magnets to hold those magnets such that the magnets are independently rotatable.

Each magnet may be of electromagnetic or permanent type, and retaining means for each magnet may be preferably provided for maintaining the associated portion of the section of flexible beam conduit in its predetermined position with respect to the magnetic poles of the magnet.

BRIEF DESCRIPTION OF THE DRAWING The invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a plan view, partly in section of a device for deflecting a beam of charged particles, arranged and operated in accordance with the principles of the prior art;

FIG. 2 is a diagrammatic plan view, partly in section of a device for deflecting a beam of charged particles, arranged and operated in accordance with the principles of the invention with the section taken along the line II-lI of FIG. 4;

FIG. 3 is a view similar to FIG. 2 illustrating the device of FIG. 2 in its curved state;

FIG. 4 is an enlarged cross sectional view of the device shown in FIGS. 2 and 3 with parts illustrated in elevation; and

FIG. 5 is an enlarged fragmental sectional view of a supporting member which may be used in the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing and FIG. 1 in particular it is seen that a section 10 of beam conduit is curved into a predetermined fixed curvature to guide a beam of charged particles (not shown) along the curved longitudinal axis of the section. An annular electromagnet 12 having its geometry conformed to the predetermined fixed curvature encloses the section of conduit 10 to establish a magnetic field for deflecting the beam of charged particles within the section 12 and only along the curved axis thereof in the well-known manner. It will be readily appreciated that a device illustrated permits the beam of charged particles to be deflected only with a predetermined fixed curvature corresponding to the curvature of the section of conduit. Thus it has been particularly inconvenient for the purposes of utilizing the beam of charged particles in the fields of industries and medical treatments because the curvature is inflexible.

The invention contemplates to eliminate the abovementioned inconvenience.

Referring now to FIG. 2 there is illustrated a deflection device constructed in accordance with the principles of the invention. The arrangement illustrated comprises a section 20 of flexible beam conduit which may be for example in the form of a bellows, and a'plurality of annular electromagnets 22 disposed in juxtaposed relationship and encircling the substantial portion of the flexible section 20. Each of the electromagnets 22 has a pair of opposite main faces tilted toward each other to form a convergent angle of 0 therebetween and adjoins the succeeding electromagnet through a supporting member interposed therebetween. The supporting member is schematically designated by the reference numeral 24 and functions to hold the associated electromagnets 22 in place while permitting the electromagnets to be independently rotated. The supporting member may be preferably of a ball bearing type such as described hereinafter in conjunction with FIG. 5.

In FIG. 2 the electromagnets 22 are shown as being placed in line such that the smaller ends of their cross sections alternate with the larger ends thereof whereby the common axis substantially lies on the longitudinal section 20 of beam conduit. One exciting winding 28 is disposed around each of the pole pieces 26 of the electromagnet 22 for exciting the latter. A pair of retaining members 30 of any suitable non-magnetic material such as non-magnetic stainless steel, copper or the like are suitably fixed in opposite relationship at both ends to the opposite pole pieces 26 of each electromagnet 22 and have the intermediate portions complementary in shape to the section 20 of beam conduit to sandwich the latter therebetween. This measure ensures that the opposite pole pieces have the adjacent portion of the section 20 maintained in its predetermined position with respect thereto. In other words, the retaining members 30 serves to prevent the flexible section 20 of beam conduit from escaping from the electromagnets 22.

With the arrangement illustrated, it will be readily appreciated that each of the electromagnets 22 can be rotated through any desired angle and independently of the other electromagnets and positioned in the rotated position by means of the associated supporting members 24. For example, by rotating alternate ones of the electromagnets 22 through 180 degrees the device can be readily changed from its position where they are placed in line and the section 20 of flexible conduit is maintained substantially straight as shown in FIG. 2 to its position where the electromagnets are placed in curved line into which the section is also curved as a result of the angular displacement of the electromagnets.

During the operation of changing the configuration of the flexible conduit through the rotational movement of the selected electromagnets the physical separation of the section from the electromagnets permits the former to be curved into the desired configuration without compulsion while at the same time the retaining members 30 ensures that any portion of the section 20 of flexible conduit is prevented from occupying its position offset from the asciated electromagnet 20-.

Since each of the electromagnets 22 is operated to deflect a beam of charged particles by one unit as previously described, the electromagnets in their positions as illustrated in FIG. 3 successively deflect a beam of charged particles travelling within the curved section 20 in incremental manner until the beam leaves the section. For example, assuming that n electromagnets have a common convergent angle as previously defined, the arrangement of FIG. 3, can deflect the beam of charged particles through the total angle of 119 which is a maximum angle of deflection obtainable by the same. Also it will be appreciated that in this case the present device can be inexpensively constructed.

It is to be understood that, selected ones of the electromagnets 22 can be rotated with respect to the adjacent electromagnets to curve the section 20 of flexible conduit through any desired angle not only two-dimensional but also three-dimensional within a maximum possible angle such as the angle of mi in the previous case with the result that the particular beam of charged particles are deflected within the section thus curved and along the longitudinal axis thereof.

FIG. shows one form of the supporting member 24. The supporting member 24 is of a ball bearing type and includes an outer race 32 fixedly secured to the outer peripheral portion of one of two adjacent electromagnets 22 an inner race 34 fixedly secured to the other electro magnet 22 and a plurality of balls 36 arranged for example in two rows with an annular partition 38 projecting from the outer race 32 to separate two ball rows from each other.

The invention is applicable to the deflection of beams of charged particles generated by various means. For example, the invention can be effectively used in irradiating a subject by a particle accelerator. In this case, the beam of charged particles from the accelerator is possible to irradiate a body to be irradiated in every possible direction without the necessity of moving the accelerator. If the accelerator is operatively associated with a section of any suitable straight tube for guiding the beam of charged particles from the accelerator then that beam is allowed to be conveyed from that chamber having the accelerator disposed therein to another chamber.

It is to be understood that, if desired, any suitable permanent magnets, any suitable electromagnetic deflection coils or any suitable electrostatic deflection means may be equally used in place of the illustrated electromagnets 22. Further the unit deflection electromagnets 22 need not have a common convergent angle, and any suitable combination of electromagnets 22 and/ or the equivalent having suitable different convergent angles are possible.

What we claim is:

1. In a flexible device for deflecting a beam of charged particles, the combination comprising a section of flexible beam conduit for guiding a beam of charged particles therewithin, a plurality of annular magnets disposed in juxtaposed relationship and each encircling a respective axial portion of said section of flexible beam conduit, each of said magnets having a pair of opposite main faces tilted toward each other for imparting a deflection to the beam of charged particles, and supporting members interposed respectively between adjacent magnets, said supporting members including means for rotatably joining adjacent magnets.

2. A flexible device for deflecting a beam of charged particles as claimed in claim 1, wherein said magnets are electromagnets.

3. A flexible device for deflecting a beam of charged particles as claimed in claim 1, wherein said magnets are permanent magnets.

4. A flexible device for deflecting a'beam of charged particles as claimed in claim 1, further comprising retaining means for each of said magnets to maintain the associated portion of said section of flexible beam conduit in a predetermined position with respect to the magnet poles of the magnet.

5. A flexible device for deflecting a beam of charged particles as claimed in claim 1, wherein said means for rotatably joining adjacent magnets includes ball bearing means.

References Cited UNITED STATES PATENTS GEORGE HARRIS, Primary Examiner US. Cl. X.R. 31376, 84 

